The present invention relates generally to manufacturing integrated circuits and the like, and more particularly to a vacuum debris removal system for an integrated circuit manufacturing device.
In the manufacturing of semiconductor devices and integrated circuits, multiple layers of different types of materials, such as conductive, semiconductive, and insulation type materials, are deposited or formed on a substrate, semiconductor die or wafer. Selected portions of the different layers may be removed in predetermined patterns by etching, photolithography or other material removal techniques, or ions or charged particles may be implanted in selected areas to form different semiconductor regions and components of a semiconductor device or integrated circuit. In a photolithographic process, a layer of resist material is formed on an underlying layer of material from which material is to be removed or etched in a predetermined pattern. The resist layer may be exposed to a beam of light, typically ultraviolet light, through a mask so that only selected portions of the resist layer are exposed or the beam of light maybe focused on the resist layer and the semiconductor wafer is moved to expose the selected portions of the resist layer. The semiconductor wafer is then developed to remove the unexposed portions of the resist layer. The underlying layer of material is exposed according to a predetermined pattern after the unexposed portions of the resist layer are removed. The underlying layer or layers of material may then be removed or etched using the remaining portions of the resist layer as mask or etch stop.
The size of the lines forming the patterns in the resist material are typically about 20 to about 100 xcexcm. Accordingly, the beam of light focused on the resist material must be very precise with little if any distortion. When the resist material is exposed to light, a chemical reaction occurs and particles from the resist material can be given off or xe2x80x9coutgassedxe2x80x9d with some of the particles accumulating on a lens element of the projection optics of an integrated circuit (IC) manufacturing device, such as a photolithographic camera device, microscanning device or the like. One example of such a device is a Micrascan(copyright) II/QML. The contamination of the lens element with the outgassed particles from the resist will cause lens distortion and scattering of light from the lens element. The line widths of the pattern or printed layer on the semiconductor wafer will vary as a result of the distortion creating defective products. To remove the contamination, the lens element must be cleaned which results in machine downtime and further risks to the device. If the cleaning is not done properly, both the front and back portions of the lens element could become contaminated or damaged and cleaning the lens element could make it more susceptible to future contamination. Additionally, the lenses in the projection optics of the manufacturing device could become misaligned requiring that the device be rebuilt by the manufacturer.
One known system 100 for removing debris or outgassed particles from resist material is shown in FIG. 1. FIG. 1 shows a face plate 102 for a photolithographic IC manufacturing device (not shown in FIG. 1). The face plate 102 has an exposure slit 104 formed therein through which a beam of light may be focused by projection optics of the photolithographic manufacturing device onto a semiconductor wafer (not shown). The focused beam of light exposes selected portions of a layer of resist material formed on the wafer. As previously described a chemical reaction occurs in the resist material and particles are outgassed that can contaminate a lens element of the projection optics. The debris removal system 100 includes a single stainless steel vacuum tube 106 that is bent around the exposure slit 104. The stainless steel tube 106 is one continuous tube and includes four 90xc2x0 bends with 2 long sides 108 and two shorter sides 110. The ends 112 and 114 of the stainless steel tube 106 are coupled to a vacuum pump (not shown in FIG. 1). A plurality of holes 115 are formed in the vacuum tube 106 around the perimeter of the exposure slit 104. The tube 106 may have from about 20 to about 56 holes 115 formed therein to draw away outgassed particles from the resist material.
FIG. 2 is a simulation of the air flow in the slit 104 for the tube 106 with eight holes in each long side 108 of the of the tube 106 and two holes in each short side 110. As shown in FIG. 2, two air pockets 202 and 204 are formed by the vacuum through the tube 106 with a dead air space 206 between the air pockets 202 and 204. Outgassed particles can contaminate the lens element of the manufacturing device through the dead air space 206. Additionally, the abrupt changes in air flow direction within the tube 106 caused by the four 90xc2x0 also adversely affects the suction ability and air flow dynamics within the slit 104 as shown in FIG. 2.
The system 100 with the four 90xc2x0 bends also presents some manufacturing challenges. Sharp 90xc2x0 bends are required to closely conform with the perimeter of the exposure slit 104. This requires multiple steps and a significant amount of stress can be placed on the tube 106 resulting in small openings or fissures. Additionally, air flow restrictions can occur in the area of the bends.
Accordingly, for the reason stated above, and for other reasons that will become apparent upon reading and understanding the present specification, there is a need for a vacuum debris removal system that is reliable and effectively removes contaminants and is simple and reliable to manufacture.